linux(4): Handle 64-bit SO_TIMESTAMP for 32-bit binaries

To solve y2k38 problem in the recvmsg syscall the new SO_TIMESTAMP
constant were added on v5.1 Linux kernel. So, old 32-bit binaries
that knows only 32-bit time_t uses the old value of the constant,
and binaries that knows 64-bit time_t uses the new constant.

To determine what size of time_t type is expected by the user-space,
store requested value (SO_TIMESTAMP) in the process emuldata structure.

MFC after: 2 weeks